story: It was only in the 1980s that digital telephony transmission networks became possible, such as with ISDN networks, assuring a minimum bit rate (usually 128 kilobits/s) for compressed video and audio transmission. During this time, there was also research into other forms of digital video and audio communication. Many of these technologies, such as the Media space, are not as widely used today as videoconferencing but were still an important area of research. The first dedicated systems started to appear in the market as ISDN networks were expanding throughout the world. One of the first commercial videoconferencing systems sold to companies came from PictureTel Corp., which had an Initial Public Offering in November, 1984. 
  
  The MC controls the conferencing while it is active on the signaling plane, which is simply where the system manages conferencing creation, endpoint signaling and in-conferencing controls. This component negotiates parameters with every endpoint in the network and controls conferencing resources. While the MC controls resources and signaling negotiations, the MP operates on the media plane and receives media from each endpoint. The MP generates output streams from each endpoint and redirects the information to other endpoints in the conference.
questions: What company had an IPO in 1984?
questions: What do they do?
questions: When did digital telephony transmission networks begin?
questions: What were the 1st networks?
questions: What was the minimum bit rate?
questions: For what type of transmission?
questions: What was also researched?
questions: What controls conferencing?
questions: In which plane?
questions: Does something work on the media plane?
questions: What does?
answers: PictureTel Corp
answers: PictureTel Corp., which had an Initial Public Offering in November, 1984.
answers: commercial videoconferencing systems
answers: One of the first commercial videoconferencing systems sold to companies came from PictureTel Corp., which had an Initial Public Offering in November, 1984.
answers: in the 1980s
answers: It was only in the 1980s 
answers: ISDN networks
answers:  The first dedicated systems started to appear in the market as ISDN networks 
answers: 128 kilobits/s
answers:  assuring a minimum bit rate (usually 128 kilobits/s)
answers: compressed video and audio
answers:  for compressed video and audio transmission
answers: other forms of digital video and audio communication
answers: During this time, there was also research into other forms of digital video and audio communication
answers: The MC
answers: The MC controls the conferencing
answers: signaling
answers: while it is active on the signaling plane
answers: the MP
answers: While the MC controls resources and signaling negotiations, the MP operates on the media plane and receives media from each endpoint
answers: the MP
answers: . While the MC controls resources and signaling negotiations, the MP operates on the media plane and receives media from each endpoint.